The relation of wind stress curl and meridional transport in the Benguela upwelling system

- Relation of meridional transport and wind stress curl in the Benguela region
- Comparison of a 9 year time series of modeled meridional transport and wind stress curl
- Analysis of annual and semi-annual cycles of meridional transport and wind stress curl

Spatially high resolved wind data reveals the existence of a very pronounced and persistent cyclonic (negative) wind stress curl (WSC) along the southwest African coast. Several theoretical studies have shown that negative WSC modifies the meridional currents in eastern boundary systems significantly. Since the water mass composition on the southwest African shelf is primarily controlled by the meridional currents, understanding the relation between WSC and the meridional advection is of great importance for the Benguela ecosystem. In this study, we use a regional general circulation model that is validated with observations in order to study the effect of cyclonic WSC on the meridional transport along the southwest African coast. We show that there is a connection between the meridional transport and the WSC on a seasonal time scale in the northern Benguela upwelling system (BUS). The meridional transport follows the annual and semi-annual cycles of the WSC between 20° S and 25° S. The cyclonic WSC in the northern BUS may therefore support a southward advection of tropical waters into the upwelling system.